n8n: Webhook Forgery on Github Webhook Trigger
## Impact An attacker who knows the webhook URL of a workflow using the GitHub Webhook Trigger node could send unsigned POST requests and trigger the workflow with arbitrary data. The node did not implement the HMAC-SHA256 signature verification that GitHub provides to authenticate webhook deliveries, allowing any party to spoof GitHub webhook events. ## Patches The issue has been fixed in n8n versions 2.5.0 and 1.123.15. Users should upgrade to one of these versions or later to remediate the vulnerability. ## Workarounds If upgrading is not immediately possible, administrators should consider the following temporary mitigations: - Limit workflow creation and editing permissions to fully trusted users only. - Restrict network access to the n8n webhook endpoint to known GitHub webhook IP ranges. These workarounds do not fully remediate the risk and should only be used as short-term mitigation measures.
describes (1)
Related CVEs.
| ID | severity | exploitable | ||
|---|---|---|---|---|
| CVE-2026-56357US | medium5.3 | — | ||
n8n before 1.123.15 and 2.5.0 contains a webhook forgery vulnerability in the GitHub Webhook Trigger node that fails to implement HMAC-SHA256 signature verification. Attackers who… | ||||
references
External citations — patches, advisories, analysis.
- https://github.com/n8n-io/n8nPACKAGE
- https://github.com/n8n-io/n8n/commit/a19347a6bc9a96d5065ac77d25a811e46178c578WEB
- https://github.com/n8n-io/n8n/commit/afe322325502f448b33bff1db1575e4447c28a36WEB
- https://github.com/n8n-io/n8n/security/advisories/GHSA-mqpr-49jj-32rcWEB
- https://nvd.nist.gov/vuln/detail/CVE-2026-56357ADVISORY
- https://www.vulncheck.com/advisories/n8n-webhook-forgery-via-missing-hmac-sha256-signature-verification-in-github-webhook-triggerWEB
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